Links to download Zoom Lecture Videos and PDF files
- Lecture Date: Monday, August 23, 2021
Welcome all to the first meeting of the fall semester of Chem 12B. This class was mainly in introduction to me and overview of the course and course resources. It was a good start today with lots more to come.
- audio only m4a file
- video with audio mp4 file
- No notes taken today
- Lecture Date: Wednesday, August 25, 2021
Lecture was cancelled for this date as I had an emergency vet appointment that took place.
- Lecture Date: Monday, August 30, 2021
Before beginning lecture I wanted to assess where the class stands on the previous information. We looked at doing problems from the alkene chapter to assess the strength of the class.
- Lecture Date: Wednesday, September 1, 2021
Today we really started lecture in earnest. After doing a couple of days of alkene problems, both in lab and on Monday in lecture, I decided that the class could really benefit from a fresh look at the alkenes, so that&s where we are going to start. Today we started electrophilic addition to alkenes. We covered hydration reactions, halogenation, 1,2-hydride shifts, and 1,2-alky shifts that can occur with carbocation formation.
- Lecture Date: Wednesday, September 8, 2021
Continuing on with the Alkene today, we covered oxymercuration-demercuration, hydroboration with BH3•THF, hydroboration with 9-BBN, the differences between regiospecific, stereospecific, and enantiospecific reactions, and finally a quick look at halogenation with peroxide. We'll discuss the halogenation with peroxide in more detail on Monday.
- Lecture Date: Monday, September 13, 2021
Today we picked up where we left off on Monday with a closer look at free radicals. We made a comparison of free radicals to carbocations and noted the similarities in structure and the similarities in stabilization factors. We have a whole chapter on free radical coming up after the alkyne chapter, so much will be saved until then. We moved into halogenation and the anti addition resulting from the formation of a cyclic bromonium ion. From there we looked at several similar reactions with hypochlorus acid and hypobromous acid, the use of N-Bromosuccinamide (NBS) and N-Chlorosuccinamide (NCS). Ozonoysis was the last reaction that we closed out with.
- Lecture Date: Wednesday, September 15, 2021
We closed out the alkene chapter today with a look at the last few reactions. Today we looked at dihydroxylation with osmium tetroxide, epoxidation with MCPBA, and finally catalytic hydrogenation with hydrogen gas and metal catalyst. We ended the session by creating a star chart to capture all the reactions on a single page. There are additional reactions that are for the alkene chapter that we pick up in the organometallic chapter, but that will be down the road a bit.
- Lecture Date: Monday, September 20, 2021
We started out look at the alkynes today. For each reaction of the alkynes we start by looking at the analogous reaction in the alkene and then showing the similarities and differences within the alkynes. Today's reactions included formation of alkynyl anions by deprotonation with amide base, hydrohalogenation, double dehydrohalogenation, and hydration to form aldehydes and ketones by tatomerization.
- Lecture Date: Wednesday, September 22, 2021
No lecture for today as I was tied up with a chemical waste pickup at Cabrillo.
- Lecture Date: Monday, September 27, 2021
Today we finished up our look at the alkyne reactions. The reactions that we cover in this lecture are catalytic hydrogenation, hydrogenation with dissolving metals, and ozonalysis. We concluded the chapter by making a star chart for the alkynes. We then started our look at simple synthesis ideas involving alkenes and alkynes.
- Lecture Date: Wednesday, September 29, 2021
We started Chapter 11, Free Radicals today. We covered structure and stability of free radicals. We looked at common reaction step patterns, the mechanism of chlorination, radical initiators, radical inhibitors, and finally the regioselectivity of halogenation. In the regioselectivity we examined the differences in selectivity of chlorination versus bromination which took us into a good review of Hammond Postulate.
- Lecture Date: Monday, October 4, 2021
Today we finished our look at free radical reactions. The topics today included the stereochemistry of free radical brominations, allylic halogenation, a little bit about organic peroxide formation, polymerization, and radical stability supported by both traditional electron withdrawing and electron donating groups.
- Lecture Date: Wednesday, October 6, 2021
We started the alcohol chapter today. We started off with nomenclature, classification, physical properties, acidity, and eventually worked our way into the synthesis of alcohols. For the synthesis we reviewed all of the reactions today that produce alcohols from various starting functional groups, and then turned our attention to reduction of carbonyl compounds.
- Lecture Date: Monday, October 11, 2021
Today we looked at synthesis of alcohols by reduction. We examined reduction of aldehydes, ketones, and esters. The reduction of esters took us to a discussion of the synthesis of diols of various substitution patterns. We took an in depth look at the formation of alcohols of different substitution patters using Grignards and various stating carbonyl compounds. We ended the lecture with a look at the need and use of protecting groups in the synthesis of alcohols.
- Lecture Date: Wednesday, October 13, 2021
Today was entirely focused on the use of protecting groups for alcohols. We covered four main types of protecting groups - silyl ethers, acetals, esters, and finally benzyl groups. At the conclusion of the lecture we showed an example of synthesis that required a protection/deprotection strategy with two different types of protecting groups that demonstrated how to make choices regarding which protecting groups to use.
- Lecture Date: Monday, October 18, 2021
Today we took on part 2 of alcohols - the synthetic use of alcohols. In this chapter we look at all the things that we can convert alcohols into with a considerable focus on oxidations.
- Lecture Date: Wednesday, October 20, 2021
Today we focused on ethers and epoxides. This was the first day on what is likely a 2 day lecture. Today we covered nomenclature, physical properties, crown ethers, Williamson Ether Synthesis, and synthesis of epoxides. Towards the end of the lecture we were working on the Sharpless asymmetric epoxidation. We'll finish up the Sharpless reaction in the next class.
- Lecture Date: Monday, October 25, 2021
Looking back over the notes this lecture covers Sharpless Asymmetric Epoxidation, expoxides as electrophiles in general, epoxides reacting under acidic conditions versus basic conditions, as well as some synthesis and big picture takeaways from the chapter.
- Lecture Date: Wednesday, October 27, 2021
Today marks our start on spectroscopy. We start with an overview of how structure elucidation is done utilizing different types of spectroscopy for different parts of information. We then look at an overview of nuclear magnetic resonance, experimental theory and design and instrumentation. As a practical component we start to look at the idea of chemical equivalence for hydrogen and carbon within a molecule.
- Lecture Date: Monday, November 1, 2021
This lecture is following the morning lab lecture where we started looking at simple 1H-NMR and 13C-NMR. It would be good to watch the two lectures contiguously starting with the morning lab lecture. In this lecture we introduce the concept of spin-spin coupling in 1H-NMR. Topics include origin of spin-spin coupling, definition of J values, tree diagrams for predicting splitting patterns, and common observed patters predicted by Pascal's triangle.
- Lecture Date: Monday, November 3, 2021
This lecture follows from the morning lab lecture. Several spectral analysis techniques were presented in the morning lab, and are followed through on here in this lecture. The two lectures are best viewed contiguously start with the morning lab lecture. In this lecture we introduce the idea of protic hydrogens "exchanging" with D2O in an NMR experiment designed to show the presence of protic hydrogens. We took a closer look at patters for aromatic ring protons for monosubstituted benzene rings and disubstituted benzene rings.
- Lecture Date: Monday, November 8, 2021
For this class we focused on some slightly more challenging NMR problems from the Organic Structure Elucidation website. Here we looked at problems 64 and 19, with 64 being listed as beginning and 19 as intermediate. These two problems were a step up in information from the WebSpectra problems. Just a few more pieces of data to juggle, but they are solved by exactly the same process.
- Lecture Date: Wednesday, November 10, 2021
One last day on NMR problem solving examples. Today we took a faster look at numerous disubstituted aromatic patterns. We focused on showing multiple examples of ortho-, meta-, and para-substituted aromatic patterns. We then did a more complicated trisubstituted aromatic compound example showing how to coordinate the strength of the electron withdrawing group substituents with the aromatic proton signals.
- Lecture Date: Monday, November 15, 2021
Today we moved from NMR to mass spectrometry. We take a look at the basics of how mass spec works, how to find the molecular ion mass and the corresponding molecular ion formula. We also take a basic look at fragmentation processess that can give more information regarding the presence of functional groups within the molecule.
- Lecture Date: Wednesday, November 17, 2021
Today we look at some additional mass spectrometry concepts including how to use isotope information, heterolytic alpha cleavages, and our first example of working a problem from scratch using mass spec, NMR and IR.
- Lecture Date: Monday, November 22, 2021
The plan was to move on to aromaticity today, however a few well timed questions indicated that a little more time needed to be spent on Mass Spec, and so that is what we did. One last day on mass spec.
- Lecture Date: Wednesday, November 24, 2021
Today we covered aromaticity. Thus far in the course we have considered aromatic to be a benzene ring. Today we look at what actually makes a molecule aromatic and they many different molecule structures that can be aromatic. In this lecture we take a look at Hückel's Rules, Frost's Circle and many examples of aromatic configurations.
- Lecture Date: Wednesday, November 29, 2021
After covering what aromaticity is, today we start looking at reactions of aromatic rings. Principally we look at the Birch Reduction and Electrophilic Aromatic Substitution (EAS). Of the two reactions we spend significantly more time on the EAS reactions.
- Lecture Date: Wednesday, December 1, 2021
Last lecture of the semester! In this lecture we take a deeper dive into EAS reactions and look at selectivity of substitution position, Friedle Crafts Acylations, and Friedle Crafts Alkylation reactions. We also look at how we can control substitution patters when adding multiple substituents to achieve a target molecule.